/**
 * Copyright (C) 2011 Whisper Systems
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.appspot.eusms.service;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.provider.Telephony;
import android.telephony.SmsMessage;
import android.util.Log;

import com.appspot.eusms.protocol.WirePrefix;
import com.appspot.eusms.sms.IncomingTextMessage;
import com.appspot.eusms.util.TextSecurePreferences;
import com.appspot.eusms.util.Util;

import java.util.ArrayList;

public class SmsListener extends BroadcastReceiver {

    private static final String SMS_RECEIVED_ACTION = Telephony.Sms.Intents.SMS_RECEIVED_ACTION;
    private static final String SMS_DELIVERED_ACTION = Telephony.Sms.Intents.SMS_DELIVER_ACTION;

    private boolean isExemption(SmsMessage message, String messageBody) {

        // ignore CLASS0 ("flash") messages
        if (message.getMessageClass() == SmsMessage.MessageClass.CLASS_0)
            return true;

        // ignore OTP messages from Sparebank1 (Norwegian bank)
        if (messageBody.startsWith("Sparebank1://otp?")) {
            return true;
        }

        return
                message.getOriginatingAddress().length() < 7 &&
                        (messageBody.toUpperCase().startsWith("//ANDROID:") || // Sprint Visual Voicemail
                                messageBody.startsWith("//BREW:")); //BREW stands for “Binary Runtime Environment for Wireless"
    }

    private SmsMessage getSmsMessageFromIntent(Intent intent) {
        Bundle bundle = intent.getExtras();
        Object[] pdus = (Object[]) bundle.get("pdus");

        if (pdus == null || pdus.length == 0)
            return null;

        return SmsMessage.createFromPdu((byte[]) pdus[0]);
    }

    private String getSmsMessageBodyFromIntent(Intent intent) {
        Bundle bundle = intent.getExtras();
        Object[] pdus = (Object[]) bundle.get("pdus");
        StringBuilder bodyBuilder = new StringBuilder();

        if (pdus == null)
            return null;

        for (Object pdu : pdus)
            bodyBuilder.append(SmsMessage.createFromPdu((byte[]) pdu).getDisplayMessageBody());

        return bodyBuilder.toString();
    }

    private ArrayList<IncomingTextMessage> getAsTextMessages(Intent intent) {
        Object[] pdus = (Object[]) intent.getExtras().get("pdus");
        ArrayList<IncomingTextMessage> messages = new ArrayList<IncomingTextMessage>(pdus.length);

        for (int i = 0; i < pdus.length; i++)
            messages.add(new IncomingTextMessage(SmsMessage.createFromPdu((byte[]) pdus[i])));

        return messages;
    }

    private boolean isRelevant(Context context, Intent intent) {
        SmsMessage message = getSmsMessageFromIntent(intent);
        String messageBody = getSmsMessageBodyFromIntent(intent);

        if (message == null && messageBody == null)
            return false;

        if (isExemption(message, messageBody))
            return false;

        if (!ApplicationMigrationService.isDatabaseImported(context))
            return false;

        if (isChallenge(context, intent))
            return false;

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT &&
                SMS_RECEIVED_ACTION.equals(intent.getAction()) &&
                Util.isDefaultSmsProvider(context)) {
            return false;
        }

        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT &&
                TextSecurePreferences.isInterceptAllSmsEnabled(context)) {
            return true;
        }

        return WirePrefix.isEncryptedMessage(messageBody) || WirePrefix.isKeyExchange(messageBody);
    }

    private boolean isChallenge(Context context, Intent intent) {
        String messageBody = getSmsMessageBodyFromIntent(intent);

        if (messageBody == null)
            return false;

        if (messageBody.matches("Your TextSecure verification code: [0-9]{3,4}-[0-9]{3,4}") &&
                TextSecurePreferences.isVerifying(context)) {
            return true;
        }

        return false;
    }

    private String parseChallenge(Context context, Intent intent) {
        String messageBody = getSmsMessageBodyFromIntent(intent);
        String[] messageParts = messageBody.split(":");
        String[] codeParts = messageParts[1].trim().split("-");

        return codeParts[0] + codeParts[1];
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.w("SMSListener", "Got SMS broadcast...");

        if (SMS_RECEIVED_ACTION.equals(intent.getAction()) && isChallenge(context, intent)) {
            Log.w("SmsListener", "Got challenge!");
            Intent challengeIntent = new Intent(RegistrationService.CHALLENGE_EVENT);
            challengeIntent.putExtra(RegistrationService.CHALLENGE_EXTRA, parseChallenge(context, intent));
            context.sendBroadcast(challengeIntent);

            abortBroadcast();
        } else if ((intent.getAction().equals(SMS_DELIVERED_ACTION)) ||
                (intent.getAction().equals(SMS_RECEIVED_ACTION)) && isRelevant(context, intent)) {
            Intent receivedIntent = new Intent(context, SendReceiveService.class);
            receivedIntent.setAction(SendReceiveService.RECEIVE_SMS_ACTION);
            receivedIntent.putExtra("ResultCode", this.getResultCode());
            receivedIntent.putParcelableArrayListExtra("text_messages", getAsTextMessages(intent));
            context.startService(receivedIntent);

            abortBroadcast();
        }
    }
}
